This invention relates to methods and apparatus for mitigating the danger of needle-stick and blood-splash during intravenous (IV) and similar medical procedures where a first needle is used to access a blood vessel and a second needle is used in a sampling port to draw-off samples of liquid obtained from the patient or delivered to the patient. The most common use envisaged for such methods and apparatus is in blood collection from blood donors, but the invention is also applicable to other intravenous medical procedures such as renal dialysis and the sampling of liquids from body cavities. The invention is also concerned with the design and use of sampling ports and needle guards employed in any such procedure.
In this specification, xe2x80x98needle-stickxe2x80x99 refers to the pricking of a phlebotomist or other person with a used needle, while xe2x80x98blood-splashxe2x80x99 refers to the dripping or oozing of blood or other body liquid from a needle onto a person, or onto a surface that could come into contact with a person.
For convenience, this invention will be described with particular reference to procedures for collecting blood from donors but it will be appreciated that the invention is not necessarily confined to this context. Also for convenience, a sampling port may simply be referred to as a xe2x80x98portxe2x80x99.
The collection of blood from donors, along with other IV procedures, involves the use of a needle assembly comprising a hypodermic needle that is connected to a flexible trailing tube via a needle hub. For convenience such needle assemblies may be referred to as IV needle assemblies.
Our prior Australian patent Nos 654464 and 695517 disclose a needle guard suitable for use with blood collection procedures employing IV needle assemblies. This guard is placed on the trailing tube so that the needle can be withdrawn from a patient directly into the guard by pulling on the tube. Once fully withdrawn into to guard, the needle is automatically locked within the guard so that it cannot be removed and so that it is rendered safe against needle-stick for handling and disposal. However, blood-splash can still occur through the open end of a guard housing a used needle. It is also known to form a needle guard around the needle and hub of an IV needle assembly so that the guard is permanently attached to the needle assembly. In such guards, the unused needle can be extended from the guard for use and withdrawn into to guard after use but, again, there is the danger of blood-splash from the open end of a guard containing a used needle.
Since samples of blood must be taken for analysis at the time of blood collection, it is common practice to connect a sampling port to the trailing tube of the needle assembly and to dispose of the sampling port, needle and interconnecting tubing as a single item after use. The common port is simply a hollow moulded-plastic cylinder or barrel that has a closed base and an open top. A hollow needle is mounted in the base so that it extends axially into the barrel, the butt of the needle being connected externally of the port to the trailing tube of the needle assembly. A rubber-like sheath normally covers the port needle. To collect a blood sample, a sealed vacuum phial with a rubber-like bung is pushed into the port and onto the sheathed needle so that the port needle penetrates its sheath and the bung, causing blood (or other liquid) to be sucked into the phial from the tube of the needle assembly. When the phial is pulled out of the port, the needle is extracted from the bung, the bung reseals and the sheath springs back to cover the needle again.
While the barrel of the port is intended to shield the user from contact with the port needle, a user can inadvertently put a finger into the port and suffer needle-stick injury. It is also possible for blood to be exuded from the port needle and result in blood-splash contamination through the open end of the port. This can happen in various ways: blood can ooze through the pierced end of the sheath; the sheath may not spring back and re-cover the needle allowing blood to flow from the needle point; if more than one sample is taken, compression of the sheath by each phial after the first will force blood from the bottom of the sheath into the base of the port.
To address the danger of blood-splash from the open end of a needle guard or a sampling port, and to mitigate the danger of needle-stick from the port needle, it is known to provide push-on caps for each type of device. An example of the use of a push-on cap for a needle guard is provided by Utterberg in U.S. Pat. No. 5,112,311 and examples of the use of push-on caps for ports are provided by Coburn in U.S. Pat. Nos. 4,784,650 and 4,932,418, Chen in U.S. Pat. No. 5,752,936, Schmitt in U.S. Pat. No. 5,259,392. and Broden in WO 88/05286. While effective, the use of such caps is bothersome and time-consuming for a phlebotomist.
Another known approach to mitigation of blood-splash from needle guards relies upon the use of textured surfaces or adsorbent pads in the guards near their open ends. This is exemplified by the above mentioned Utterberg patent and our Australian patents 654464 and 695517. Similarly, to inhibit blood forced from the bottom of a port-needle sheath from oozing along the screw-thread by which the butt end of a sampling port needle is mounted in the base of the port, U.S. Pat. No. 5,782,820 to Roland discloses the use of an adsorbent washer between the flange of the threaded needle butt and the exterior of the base of the port. Such a washer does not, however, mitigate blood-splash from the open end of the port, which is the principal danger.
The invention seeks to provide means for mitigating the danger of blood-splash contamination the open end of a guarded IV needle and/or from the open end of a sampling port.
From one aspect, the present invention comprises a method of mitigating the danger of blood-splash contamination from the open end of a needle guard and/or from the open end of a sampling port, the method involving inserting the open end of the needle guard into the open end of the port. Preferably, the guard is inserted so that the port needle enters the open end of the guard. The method may also include the steps of connecting the port-needle to the trailing tube of the needle assembly, taking samples from the trailing tube using vacuum phials, withdrawing the IV needle into its guard, inserting the guard into the open end of the port and/or securing the needle guard in the port against unintended removal.
From another aspect, the invention may comprise a tubular needle guard having retaining means adapted to retain the guard within a sampling port when the guard is inserted into the port open-end first. Similarly, the invention may comprise a tubular port having retaining means adapted to retain a tubular needle guard that has been inserted into the port open-end. The retaining means may comprise clips, catches, barbs or the like that are engaged by simply pushing the guard into the port, but twisting or turning the guard in the port to effect retention is also envisaged.
An adsorbent pad of material may be incorporated in the closed base of the port around the butt of the port needle and the guard may be entered into the port so that the open end of the guard is close to or presses upon the pad to reduce the likelihood that blood will find its way from the open end of the guard into the barrel of the port. In this way, substantially the full length of the port needle may be inserted into the guard and the open end of the guard may be substantially closed by the base of the port or by a pad therein. In addition to or instead of the pad, the interior of the base of the port may be coated or treated to promote the immobilisation and/or rapid clotting of blood.
It is desirable that separate guide means are formed in the barrel of the sampling port to accommodate and guide a phial and a guard during insertion into the port, at least the guide means for the phial including stop means that limits the inward travel of the phial into the port. This enables the limit for phial penetration to be set so that the bung of the phial cannot contact the base of the port or an adsorbent pad fitted in the base, since such contact may contaminate the end of the bung with blood or other liquid on the pad or base of the port. On the other hand, the use of separate guide and/or stop means allows a guard to be entered further into the port than a phial, permitting the end of the guard to be positioned in contact with or in close proximity to the base of the port or a pad fitted therein. It is also desirable to limit the penetration of a phial into the port to ensure that the needle sheath is not damaged by excessive compression.
Conveniently, the guard can have a generally rectangular section and the phial a smaller generally circular section, and the guide means can comprise grooves or channels formed in the wall of the barrel of the port that are shaped and dimensioned so that phials and guards are guided and stopped differently.
The materials employed for the port pad can be fibrous or foamed, synthetic and/or natural, so long as they are highly wettable and capable of rapidly absorbing and retaining substantial quantities of aqueous liquids (in relation to their dry weight or volume). Examples of suitable materials are cellulose fibres (natural or synthetic), plasters, clays, fired or unfired but unglazed ceramic materials, foamed materials of synthetic or natural components. Such materials may be formed into washer-like discs and pressed and/or glued into the base of the sampling port so that they are retained therein. If desired, the internal surface of the port and/or the external surface of the internal needle boss can include a recess or ridge to assist in retaining the discs.
Suitable coatings can be formed from a variety of natural or synthetic materials applied as paints or slips which dry to form porous and/or hydrophilic layers on the interior of the sampling port, preferably at or near the base thereof.
The treatments envisaged include the formation of etched or textured surfaces on the interior of the sampling ports, preferably near their closed ends were first contact with blood or other fluid which has leaked from the port needle is most likely. The etching may be effected by acid etching the exterior of the core used in moulding the port, or it may be effected by treating the interior of the port with acids, plasma discharges or the like.
The pad materials and/or the interior of the port may be impregnated, coated or otherwise treated with fine particulate minerals, such as the silicates of, sodium, potassium, magnesium and/or aluminium, titanium dioxide, diatomaceous earth. Fine powders of fired or unfired clays, cementicous materials or the like may also be employed. Preferably, such mineraliferous materials have particle sizes of less than 20 xcexc, more preferably less than 5 xcexc and most preferably of sub-micron dimensions (ie, less than 1 xcexc). As an alternativexe2x80x94or in additionxe2x80x94to the use of mineraliferous materials, this invention also envisages the use of intrinsic clotting pathways. For example, the pads may incorporate thrombin, heparinase and/or fibrinogen, or various peptides and proteins.